The Fill-Rite 400KTH1457 Kit includes a Santoprene diaphragm specifically designed for the 400B series pumps. This high-quality diaphragm ensures reliable performance and durability under various operating conditions. Santoprene is known for its excellent resistance to chemicals and temperature fluctuations, making it ideal for fuel transfer applications. This repair kit is essential for maintaining the integrity of your pump, ensuring efficient operation and compliance with industry standards. Easy to install, it helps reduce downtime and prolongs the life of your equipment.